An inertial centrifugal ratchet is disclosed in Chinese Utility Model patent CN91208227.5, wherein a magnetic ring is provided under the ratchet. The pawls stretch radially outwardly in the direction effected by the centrifugal force when gears are turning so as to mesh with the teeth of the ratchet. According to the technical solution disclosed in the patent, the ratchet can't operate reliably when the pawls do not rotate flexibly, which is due to the centrifugal force that makes the pawls stretch radially outwardly to mesh with the teeth of the ratchet.
A US patent (U.S. Pat. No. 5,205,386) disclosed a pawl and ratchet clutch with a pawl holdback means, wherein a magnet is disposed radially outwardly of associated pawl meshing end. The pawls stretch radially outwardly by the centrifugal force when the driving shaft rotates at a speed above a desired value. Once the pawl contacts with associated magnet, it will be held by said magnet. Such clutch still utilizes the spring force to drive pawl to swing and mesh with the teeth of said ratchet. Therefore, the spring will be loaded frequently and repeatedly in case of frequently overrunning condition with heavy load. The spring will be fatigue failure quickly and make the clutch be malfunction. In addition, mechanical contact will take place between the magnet and the end of pawl of the clutch during operation, which makes the two parts impinge each other frequently. Such contact and impingement cause damage on magnet or make the magnet become hot. The clutch could be malfunction when the magnet is damaged. The magnet will shrink when it is heated and then is relaxed, which will also make the clutch be malfunction.